(1) Field of the Invention
The invention is directed to a closing cylinder with a cylinder core for insertion of a key for resetting closing followers in the cylinder core from their blocking engagement in a bearing sleeve. The there provided overload blocker is to protect the closing cylinder against damages, in case unauthorized persons perform forced rotations at the cylinder core by way of a break-in tool. The overload blocker responds to a certain limiting torque. In a normal case, at a rotation of the cylinder core by way of a proper key, the torque is transferred to a drive member of the closing cylinder, which drive member performs the desired functions at the vehicle. If however the limiting torque has been surpassed by forced rotations without key, then the overload blocker passes into an overload case, where the torque does not pass to the driven member of the closing cylinder based on internal decoupling. Then no function is performed in the vehicle. The cylinder core together with the bearing sleeve fixed against rotation relative to the cylinder core is idle running.
(2) Description of Related Art including information disclosed under 37 CFR 1.97 and 1.98
The German patent document DE 38 27418 C2 shows such a closing cylinder. Here the overload blocker comprises a release sleeve with a sliding claw connected in fact axially fixed but rotatable to the release sleeve. The sliding claw has a coupling part, which engages a counter coupling part of the closing cylinder based on a spring force. Profiled locking cams and counter profiled locking recesses are disposed between the release sleeve and a bearing sleeve, wherein the release sleeve is shifted parallel between its normal position and its overload position through the locking recesses. A helical spring encloses a core piece of the driven member and of the sliding claw and takes care of a pressure on all sides between an inner flange of the release sleeve and an outer flange of the sliding claw. Also the sliding claw is shifted parallel thereby during a transition from the normal case to the overload case.
The locking cams effective for decoupling the carrier relative to the closing cylinder and the locking recesses between the release member and the bearing sleeve have to be kept small for reasons of space limitations in the known closing cylinder. Therefore various different limiting torques result with a production of the known closing cylinder. The straying of these values makes it more difficult to furnish a guarantee relative to the functional security of the closing cylinder.